Visa withdrawl issue

Hello friends. Can i have one small help? Currently, i am in student visa status from bridging A and waiting my visa grant from bridging visa c 489 nt regional. So in that case can i withdraw my student visa and stay on bridging visa c? I try to contact immigration but they said that no right to advice so pretty confuse with rule. Thanks.plz
It sure is confusing and hard to clarify anything with immigration customer service. please try sending these guys an email with your question query@iscah.com they might be able to help you clarify this.
As far as i know if you cancel ur student visa then u loose ur bridging visa as well. what does ur bridging visa say? is it in effect?. coz student visa supercedes bridging visa. if student visa expires than the bridging visa kicking in. But if you cancel student visa u may loose the bridging visa